This invention relates generally to surgical instruments and, more particularly, to a cutting and coagulating forceps.
Electrosurgery involves the application of electrical energy to tissues. Water is evaporated from tissues during electrosurgery, and with proper control of the intensity, frequency and duration of the applied energy, a surgeon can either coagulate or cut tissues.
A number of expired patents disclose electrocautery forceps having a pair of U-shaped jaws and a cutting wire which is advanced between the arms of the jaws to cut tissue clamped between them. A more recent U.S. Pat. No. 5,258,006, discloses an electrosurgical bipolar forceps having a pair of jaws which grasp and coagulate tissues, but not a cutting blade. The jaws are operated by a camming action produced when the jaws are moved along the tool by operating a lever on the tool body.
In the present invention, a purely mechanical shielded cutting blade is employed, in conjunction with bipolar coagulating jaws. Both the blade and the jaws are independently movable along the axis of the tool. A high frequency voltage is applied across the opposed jaws after they have grasped a tube, ligament, or other tissue, to coagulate the tissue; once coagulated, the tissue is then mechanically cut by advancing the blade.
To enable the surgeon to cut completely through tissue clamped by the jaws, the blade must not travel beyond the coagulated area; otherwise, bleeding will occur. Ideally, the blade should have as much travel as possible within the jaws, but the blade must never actually contact the jaws, so a stop has been provided to limit forward blade motion. With this invention, the stop is movable, and affixed to the jaw actuating lever, so that regardless the location of the jaws, the blade is always stopped short of contact with the jaw tips. Thus, the blade stop moves to compensate for changes in jaw position.